The use of infusion sets to administer solutions to patients is well known in the medical arts. Infusion sets are used for I.V. infusion as well as enteral and parenteral applications, for example. Enteral feeding pumps are used to provide patients with nutrition and medication when they are unable, for a variety of reasons, to eat normally. Parenteral (intravenous) solutions are provided to patients to ensure adequate hydration and to provide needed nutrients, minerals and medication. Often, the infusion set is placed in a free standing arrangement in which gravity forces the solution into the patient. The rate at which the solution enters the patient can be roughly controlled by various clamps, such as roller clamps, which are currently available on the market.
In many applications, it is necessary to precisely control the amount of solution which enters the patient. When this is the case, a regulating device, such as an enteral feeding pump or an IV pump, is placed along the infusion set to control the rate at which the solution is fed to the patient. In applications where a pump, etc., is used, the clamp used to control the flow of the solution (if present on the infusion set) is typically opened to its fullest extent to prevent the clamp from interfering with the proper functioning of the pump. The clamp is opened with the expectation that the enteral feeding pump will control fluid flow through the infusion set. However, emergencies or other distractions may accidentally remove the infusion set from the pump or prevent the medical personnel from properly loading the infusion set in the enteral feeding pump.
When the infusion set is not properly loaded in the pump and the clamp has been opened, a situation known as free-flow often develops. The force of gravity or a pressure differential causes the solution to flow freely into the patient unchecked by the pump or other regulating device. Under a free-flow condition, an amount of solution many times the desired dose can be supplied to the patient within a relatively short time period. This can be particularly dangerous if the solution contains medicine as this could result in an overdose of medication. Free flow can also be dangerous where the patient's body is not physically strong enough to adjust to the large inflow of solution. There have been numerous occasions in which a patient has died due to the over-infusion of fluid during a given amount of time. Thus, preventing an undesirable free-flow state is highly desirable.
Numerous devices have been developed in an attempt to prevent free flow conditions. Such devices, however, add to the overall cost of the infusion set and some provide only marginal protection against free flow. Others may have other limitations which limit the usefulness of the occluder.
One popular anti-free flow occluder is described in U.S. Pat. No. 5,704,584 (Winterer et al.). The '584 patent teaches an occluder which is disposed around the outside of an infusion set to selectively prevent fluid flow. The occluder is biased into a closed position wherein the occluder stops flow through the infusion set. The biasing can be overcome by manually holding the occluder open, or by mounting the occluder in a pump and then closing a door so that the door holds the occluder open. The '584 patent describes the general use of occluders in infusion pumps.
While preventing unintended free-flow situations is important, there are also times in which a free-flow condition is desired. This may be the case where a patient's heart has stopped or in other emergency situations where quick corrective action is desired. Often medicines will be injected into an IV solution being administered to the patient with the desire that the solution and medicine enter the patient as quickly as possible. If the infusion set uses one of the above referenced occluders, the medical staff must ensure that free-flow conditions are being allowed. This may mean removing the infusion set from the pump in which it is housed and manually holding open the occluder. Obviously, this is not desirable, as each member of the medical staff has important duties during an emergency situation. Thus, it is desirable for medical staff to be able to lock the occluder open in an emergency or other situation in which a free-flow condition is specifically desired.
Several types of occluders can be locked in an open position. One such occluder is biased closed and designed to accept a pin into a pair of apertures to hold the occluder in an open position. Such occluders, however, are disadvantageous because the pin can be lost during the commotion involved with an emergency and the occluder may be left in a biased closed condition.
Another known occluding system uses a spring which is biased to pinch closed the tubing of an infusion set. The spring can be pushed into an open position where it allows flow through the infusion set by pressing down on a locking trigger. The locking trigger can also be moved into a locked position wherein the spring is held in an open position. The occluding system, however, is disadvantageous, as it is relatively bulky. Additionally, if the trigger is disposed in the locked open position, the module cannot be properly loaded into a pump, as the pump door will not close.
There is a need for an occluder which allows for greater control and flexibility in selecting an open or closed occluder position. There is a need for an occluder which may be controlled electronically as well as mechanically, allowing a pump or other device attached to the occluder to selectively allow or prevent flow through an infusion tube. There is a need for an occluder which automatically occludes flow through a tube if power is lost or if the tubing set is removed from the pumping device, preventing the uncontrolled flow of fluids in such a situation. There is also a need for such an occluder which is relatively inexpensive and which is easy to use.